Low threshold voltage cmos device

ABSTRACT

A semiconductor device including an NMOS region and a PMOS region; the NMOS region having a gate structure including a first high-k gate dielectric, a first work function setting metal and a gate electrode fill material; the PMOS region having a gate structure comprising a second high-k gate dielectric, a second work function setting metal and a gate electrode fill material; wherein the first gate dielectric is different than the second gate dielectric and the first work function setting metal is different than the second work function setting metal. Also disclosed are methods for fabricating the semiconductor device which include a gate last process.

BACKGROUND

The exemplary embodiments relate to semiconductor devices and, moreparticularly, to complementary metal oxide semiconductor (CMOS) deviceswith dual gate dielectrics and dual-metal gate structures andfabrication methods therefor.

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment, as examples. Semiconductor devices are typicallyfabricated by sequentially depositing insulating (or dielectric) layers,conductive layers, and semiconductive layers of material over asemiconductor substrate, and patterning the various layers usinglithography to form circuit components and elements thereon.

A transistor is an element that is utilized extensively in semiconductordevices. There may be millions of transistors on a single integratedcircuit (IC), for example. A common type of transistor used insemiconductor device fabrication is a metal oxide semiconductor fieldeffect transistor (MOSFET).

Early MOSFET processes used one type of doping to create either positiveor negative channel transistors. More recent designs, referred to ascomplimentary MOS (CMOS) devices, use both positive and negative channeldevices, e.g., a positive channel metal oxide semiconductor (PMOS)transistor and a negative channel metal oxide semiconductor (NMOS)transistor, in complimentary configurations. A PMOS transistor may alsobe referred to as a PMOSFET or PFET while an NMOS transistor may bereferred to as an NMOSFET or NFET. An NMOS device negatively charges sothat the transistor is turned on or off by the movement of electrons,whereas a PMOS devices involves the movement of electron vacancies.While the manufacture of CMOS devices requires more manufacturing stepsand more transistors, CMOS devices are advantageous because they utilizeless power, and the devices may be made smaller and faster.

Dual work function gates are advantageously used in semiconductordevices having both PMOS and NMOS transistors. Some work functions thatenable optimal operation of both PMOS and NMOS transistors are required.The optimal work function for a metal gate electrode will differdepending upon whether it is used to form an NMOS transistor or a PMOStransistor. For this reason, when the same material is used to makemetal gate electrodes for NMOS and PMOS transistors, the gate electrodesdo not demonstrate the desired work function for both types of devices.It may be possible to address this problem by separately forming metalgate electrode of the NMOS transistor from a first material and metalgate electrode of the PMOS transistor from a second material. The firstmaterial may ensure an acceptable work function for the NMOS gateelectrode, while the second material may ensure an acceptable workfunction for the PMOS gate electrode.

BRIEF SUMMARY

The various advantages and purposes of the exemplary embodiments asdescribed above and hereafter are achieved by providing, according to afirst aspect of the exemplary embodiments, a semiconductor device. Thesemiconductor device includes an NMOS region and a PMOS region; the NMOSregion having a gate structure comprising a first high-k gatedielectric, a first work function setting metal and a gate electrodefill material; the PMOS region having a gate structure comprising asecond high-k gate dielectric, a second work function setting metal anda gate electrode fill material; wherein the first gate dielectric isdifferent than the second gate dielectric and the first work functionsetting metal is different than the second work function setting metal.

According to a second aspect of the exemplary embodiments, there isprovided a method of making a semiconductor device. The method includesproviding a substrate having an NMOS region and a PMOS region; forming ahigh-k dielectric layer over the NMOS region and the PMOS region;incorporating a metal into the high-k dielectric layer over at least oneof the NMOS region and the PMOS region wherein the metal is lanthanum ifincorporated into the high-k dielectric over the NMOS region and themetal is aluminum if incorporated into the high-k dielectric dielectricover the PMOS region; depositing a nitride or carbide layer over theNMOS and PMOS regions; depositing a silicon layer over the nitridelayer; patterning a gate structure of the nitride layer and the siliconlayer over the NMOS and PMOS regions; applying an interlevel dielectricbetween the gate structure over the NMOS region and the gate structureover the PMOS region; removing the silicon layer from the gate structureover the NMOS region and the gate structure over the PMOS region toleave an opening in the gate structures; depositing a first workfunction setting metal in the opening over the NMOS region anddepositing a second work function setting metal in the opening over thePMOS region to partially fill the openings; and depositing a fill metalto fill the openings.

According to a third aspect of the exemplary embodiments, there isprovided a method of making a semiconductor device. The method includesproviding a substrate having an NMOS region and a PMOS region; forming agate structure on each of the NMOS region and the PMOS region; applyingan interlevel dielectric between the gate structure over the NMOS regionand the gate structure over the PMOS region; removing the gate structureover the NMOS region and the gate structure over the PMOS region toleave an opening in the interlevel dielectric over each of the NMOSregion and the PMOS region; depositing at least one of: lanthanum oxidein the opening over the NMOS region, aluminum oxide in the opening overthe PMOS region; depositing a high-k dielectric in each of the openingsover the NMOS region and the PMOS region; depositing a first workfunction setting metal in the opening over the NMOS region anddepositing a second work function setting metal in the opening over thePMOS region to partially fill the openings; and depositing a fill metalto fill the openings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The features of the exemplary embodiments believed to be novel and theelements characteristic of the exemplary embodiments are set forth withparticularity in the appended claims. The Figures are for illustrationpurposes only and are not drawn to scale. The exemplary embodiments,both as to organization and method of operation, may best be understoodby reference to the detailed description which follows taken inconjunction with the accompanying drawings in which:

FIGS. 1A to 1K are cross sections illustrating the formation of a firstexemplary embodiment of a semiconductor device where:

FIG. 1A illustrates a starting substrate having NMOS and PMOS regions;

FIG. 1B illustrates the deposition of a high-k dielectric layer;

FIG. 1C illustrates several deposited layers for modifying thecomposition of the high-k dielectric layer;

FIG. 1D illustrates the starting substrate with a modified high-kdielectric layer;

FIG. 1E illustrates the deposition of a nitride layer and a siliconlayer on the starting substrate;

FIG. 1F illustrates the formation of dummy gates from the nitride layerand silicon layer;

FIG. 1G illustrates the formation of spacers and an interleveldielectric layer around the dummy gates:

FIG. 1H illustrates the removal of the silicon dummy gates;

FIG. 1I illustrates the deposition of work function setting metals;

FIG. 1J illustrates the deposition of a fill metal over the workfunction setting metals; and

FIG. 1K illustrates the planarization of the semiconductor structure.

FIGS. 2A to 2G are cross sections illustrating the formation of a secondexemplary embodiment of a semiconductor device where:

FIG. 2A illustrates a starting substrate having NMOS and PMOS regions;

FIG. 2B illustrates the formation of dummy gates;

FIG. 2C illustrates the formation of spacers and interlevel dielectricaround the dummy gates;

FIG. 2D illustrates the removal of the dummy gates;

FIG. 2E illustrates the deposition of a capping layer and a high-kdielectric layer;

FIG. 2F illustrates the deposition of work function setting metals andfill metal; and

FIG. 2G illustrates the planarization of the semiconductor structure.

FIG. 3 illustrates a process flow for fabricating the first exemplaryembodiment.

FIG. 4 illustrates a process flow for fabricating the second exemplaryembodiment.

DETAILED DESCRIPTION

CMOS devices may be made by a “gate first” process or a “gate last”process. In a gate first process, metal layers over the NMOS and PMOSareas are formed and patterned to form gate structures followed bytypical CMOS processing such as forming of the source and drain, formingspacers and depositing of the interlevel dielectric. In a gate lastprocess, a dummy gate structure is formed followed by typical CMOSprocessing including formation of the source and drain, formation ofspacers and deposition of the interlevel dielectric. Thereafter, thedummy gate structure is removed followed by deposition of a replacementgate structure.

Low threshold voltages are desirable for CMOS devices. However, lowthreshold voltages for the PMOS device are difficult to achieve with agate first process. A gate last process is beneficial for the thresholdvoltage of a PMOS device but obtaining an effective work functioncorresponding to the silicon valence band edge is still challenging.

The present inventors have proposed semiconductor devices and methods offabricating them wherein NMOS and PMOS devices are formed with dual gatedielectrics and dual-metal gate structures by a gate last process.

Referring to the Figures in more detail, and particularly referring toFIGS. 1A through 1K, there is illustrated a first exemplary embodimentemploying a gate last process. A semiconductor structure 100 is to beformed which includes a semiconductor substrate 102, an NMOS area (orregion) 104 and a PMOS area (or region) 106 as illustrated in FIG. 1A.While not important to the present invention, the channel area of theNMOS area 104 and PMOS area 106 may have been implanted as required bythe semiconductor design.

The semiconductor material making up the semiconductor substrate 102 maybe any semiconductor material, including but not limited to, silicon,silicon germanium, germanium, a III-V compound semiconductor, or a II-VIcompound semiconductor. The exemplary embodiments have applicability toboth silicon-on-insulator (SOI) and bulk semiconductor technology.

Separating the NMOS area 104 and the PMOS area 106 may be a shallowtrench isolation (STI) area 108.

The semiconductor structure 100 may also include an optional layer ofsilicon germanium 110 in the PMOS area 106. The optional layer ofsilicon germanium 110 may be referred to later on in the processing aschannel silicon germanium.

Referring now to FIG. 1B, a layer of high dielectric constant material112 is conventionally deposited. The high dielectric constant (k)material 112 may be referred to hereafter as a high-k material. Someexamples of high dielectric constant materials include but are notlimited to HfO₂, HfON, ZrO2, ZrON, HfSiOx, HfSiON, HfZrO, HfZrON. Thepresent inventors prefer HfO₂ as the high-k material. It may bedeposited to a thickness of about 10 to 30 angstroms.

In an exemplary embodiment, one or more desirable metals are driven intothe high-k material 112 overlying the NMOS area 104 and the PMOS area106. Referring now to FIG. 1C, there is shown a multilayer structure 114which includes layer 116 containing aluminum, layer 118 containinglanthanum and silicon layer 120. The aluminum-containing layer 116 maybe about 1 to 10 angstroms thick and may contain aluminum, aluminumoxide or a mixture of aluminum and titanium nitride. Thelanthanum-containing layer 118 may be about 1 to 10 angstroms thick andmay contain lanthanum, lanthanum oxide or a mixture of lanthanum andtitanium nitride. The semiconductor structure 100 including multilayerstructure 114 may be annealed at 900-1100° C. for up to 5 seconds todrive the aluminum into the high-k dielectric layer 110 over the PMOSarea 106 and drive the lanthanum into the high-k dielectric layer 110over the NMOS area 104. The silicon layer 120 seals the multilayerstructure 114 from oxidation during the annealing step. The result is tomodify the high-k dielectric layer 112 into two parts so that there is ahigh-k dielectric layer portion 122 being enriched with aluminum and ahigh-k dielectric layer portion 124 being enriched with lanthanum asillustrated in FIG. 1D.

It should be understood that the principle here is to have a dual high-kdielectric layer. While the most preferred embodiment is to have analuminum-enriched portion 122 and a lanthanum-enriched portion 124, theadvantages of the invention may be achieved by having only one of thealuminum-enriched portion 122 and the lanthanum-enriched portion 124with the other portion of the high-k dielectric layer being theoriginally deposited high-k dielectric layer 112. In this latterexemplary embodiment, one of the aluminum-containing layer 116 and thelanthanum-containing layer 118 would not be needed.

After annealing as described above, the silicon layer 120,lanthanum-containing layer 118 and aluminum-containing layer 116 wouldbe conventionally removed by etching to result in the structure shown inFIG. 1D.

Referring now to FIG. 1E, 10 to 30 angstroms of titanium nitride, oralternatively tantalum nitride, titanium carbide or tantalum carbide isconventionally deposited to form a nitride or carbide layer 126 followedby about 60 nanometers of amorphous silicon to form amorphous siliconlayer 128.

Thereafter, as shown in FIG. 1F, the titanium nitride layer 126 and theamorphous silicon layer 128 are patterned to form gate structure 130over the NMOS area 104 and gate structure 132 over the PMOS area 106.

Spacers 134, such as nitride spacers, may be added in a conventionalmanner to the gate structures 130, 132 followed by conventionaldeposition of interlevel dielectric 136. The semiconductor structure 100thus far is illustrated in FIG. 1G.

Source and drain activation may occur in the NMOS area 104 and PMOS area106. During the source and drain activation, the amorphous silicon layer128 is converted to polysilicon. The polysilicon within gate structures130, 132 is a dummy gate and must be removed and replaced by areplacement gate in a gate last process according to this exemplaryembodiment. The polysilicon (formerly amorphous silicon layer 128) maybe removed by a wet etching chemical, such as tetramethylammoniumhydroxide (TMAH), Tetraethylammonium hydroxide (TEAH), or ammoniumhydroxide (NH4OH), or by a reactive ion etching process, so that opening138 is formed in gate structure 130 and opening 140 is formed in gatestructure 132 as shown in FIG. 1H.

Work function setting metals, generally indicated by layer 142, are thendeposited within openings 138, 140. The individual layers thatconstitute the work function metals, as described hereafter, are notshown for clarity. The work function setting metals in opening 138 setthe work function around the silicon conduction band edge while the workfunction metals in opening 140 set the work function around the siliconvalence band edge. Within opening 138, 10 to 30 angstroms of tantalumnitride followed by 10 to 40 angstroms of titanium aluminum aredeposited. Alternatively, titanium aluminum nitride, tantalum aluminum,tantalum aluminum nitride, hafnium silicon alloy, hafnium nitride, ortantalum carbide may be deposited within opening 138 instead of thetitanium aluminum. Within opening 140, 10 to 30 angstroms of tantalumnitride, followed by 30 to 70 angstroms of titanium nitride and 10 to 40angstroms of titanium aluminum are deposited. Alternatively, tungsten,tantalum nitride, ruthenium, platinum, rhenium, iridium, or palladiummay be deposited within opening 140 instead of the titanium nitride andtitanium aluminum nitride, tantalum aluminum, tantalum aluminum nitride,hafnium silicon alloy, hafnium nitride, or tantalum carbide may bedeposited within opening 140 instead of the titanium aluminum. The workfunction metals may be conformally deposited, as shown in FIG. 11, ormay be nonconformally deposited.

Referring now to FIG. 1J, the remainder of the openings 138, 140 arefilled with a fill metal 144, such as aluminum, titanium-doped aluminum,tungsten, or copper

The semiconductor structure 100 is then planarized by a process such aschemical mechanical polishing, FIG. 1K.

Further middle of the line and back end of the line semiconductorprocessing may then follow.

A process flow for the first exemplary embodiment is illustrated in FIG.3. The process flow begins by providing a substrate having an NMOSregion and a PMOS region, box 302.

A high-k dielectric is formed over the NMOS region and the PMOS region,box 304.

Then, lanthanum may be incorporated into the high-k dielectric over theNMOS region or aluminum may be incorporated into the high-k dielectricover the PMOS region or both lanthanum may be incorporated into thehigh-k dielectric over the NMOS region and aluminum may be incorporatedinto the high-k dielectric over the PMOS region, box 306.

A layer of titanium nitride is deposited over the NMOS and PMOS regions,box 308, followed by deposition of silicon over the nitride layer, box310.

The nitride and silicon layers are patterned to form a dummy gate, box312.

Spacers may then be applied to the dummy gate, if desired, followed bydepositing an oxide interlevel dielectric, box 314.

The silicon is removed from the dummy gates over the NMOS and PMOS areasby a suitable etching process, box, 316.

A replacement gate process commences wherein work function settingmetals are deposited to partially fill the open areas left from theremoval of the silicon, box 318, followed by deposition of fill metal tofill the remainder of the open areas and complete the replacement gateprocess, box 320.

A second exemplary embodiment employing a gate last process isillustrated in FIGS. 2A to 2G. The starting structure for this exemplaryembodiment as shown in FIG. 2A is substantially similar to the structureshown in FIG. 1A. That is, a semiconductor structure 200 is to be formedwhich includes a semiconductor substrate 202, an NMOS area (or region)204 and a PMOS area (or region) 206.

The semiconductor material making up the semiconductor substrate 202 maybe any semiconductor material, including but not limited to, silicon,silicon germanium, germanium, a III-V compound semiconductor, or a II-VIcompound semiconductor. The present invention has applicability to bothsilicon-on-insulator (SOI) and bulk semiconductor technology.

Separating the NMOS area 204 and the PMOS area 206 may be a shallowtrench isolation (STI) area 208.

The semiconductor structure 200 may also include an optional layer ofsilicon germanium 210 in the PMOS area 206. The optional layer ofsilicon germanium 210 may be referred to later on in the processing aschannel silicon germanium.

Referring now to FIG. 2B, dummy gate structures 212, which will beremoved in a subsequent process, are shown. The dummy gate structures212 have been formed from a dummy oxide 213 and a 60 nm thick layer ofeither amorphous or polycrystalline silicon which has beenconventionally blanket deposited and then patterned. The dummy oxide maybe silicon oxide grown by atomic layer deposition (ALD) or by anneal(rapid thermal anneal, furnace anneal) under an oxygen ambient. Thedummy oxide may be nitrided by either rapid thermal anneal or plasmanitridation.

As shown in FIG. 2C, insulating spacers 214, such as nitride spacers,have been added to the dummy gate structures 212 and then an interleveldielectric 216, such as an oxide, has been blanket deposited and thenplanarized by stopping on the dummy gate structures 212.

Dummy gate structures 212 are removed by by a wet etching chemical, suchas tetramethylammonium hydroxide (TMAH), Tetraethylammonium hydroxide(TEAH), or ammonium hydroxide (NH4OH), or by a reactive ion etchingprocess, followed by a removal of the dummy oxide using a wet etchingchemical. such as diluted hydrofluoric acid (DHF) or bufferedhydrofluoric acid (BHF) to result in opening 218 over the NMOS area 204and opening 220 over the PMOS area 206 in the semiconductor structure200 as illustrated in FIG. 2D. An interfacial layer 240 of silicon oxideis conventionally grown at the bottom of the openings 218, 220 by, forexample, oxidizing the silicon in NMOS area 204 and PMOS area 206.

Thereafter, a cap layer may be added in opening 218 or opening 220 orboth opening 218 and opening 220. The cap layer 222 in the opening 218may be a 1 to 10 angstrom thick layer of lanthanum oxide while the caplayer 224 in the opening 220 may be a 1 to 10 angstrom thick layer ofaluminum oxide. While both cap layer 222 and cap layer 224 are shown inFIG. 2E as a preferred embodiment, it should be understood that theadvantages of the invention may be achieved while using only one of thecap layers 222, 224 since an advantage of the invention is to have dualgate dielectrics and this may be achieved by using only one of the caplayers 222, 224.

The cap layer 222 may be applied by depositing cap layer 222 everywhere,blocking the NMOS area 204 and then removing the cap layer 222 from thePMOS area 206 by a suitable etching process, such as dilutedhydrochloric acid (HCl) Similarly, the cap layer 224 may be applied byblanket depositing cap layer 224 everywhere, blocking the PMOS area 206and then removing the cap layer 224 from the NMOS area 204 by a suitableetching process, such as diluted ammonia hydroxide (NH4OH) The order ofdepositing cap layers 222, 224 is not important and so the cap layer 224may be deposited and patterned first followed by depositing andpatterning cap layer 222.

Next, a high-k dielectric such as those mentioned in the first exemplaryembodiment is deposited. For purposes of illustration and notlimitation, high-k dielectric layer 226 is a 10 to 30 angstrom thicklayer of hafnium oxide. The high-k dielectric layer 226 must be appliedover the cap layer(s) as shown in FIG. 2E.

Cap layers 222, 224 and high-k dielectric 226 may be applied conformallyor nonconformally. As shown in FIG. 2E, these layers have been depositedconformally.

Work function setting metals layers 228, 230, respectively, must bedeposited in the openings 218 and 220. The individual work functionmetals that constitute the work function setting metals layers 228, 230,as described hereafter, are not shown for clarity. The work functionsetting metals in opening 218 set the work function around the siliconconduction band edge while the work function metals in opening 220 setthe work function around the silicon valence band edge. In opening 218over the NMOS area 204, optional layers of 10 to 30 angstrom thicktitanium nitride and 10 to 30 angstrom thick tantalum nitride aredeposited followed by a nonoptional 10 to 40 angstrom thick layer oftitanium aluminum, which together make up the work function settingmetal layer, generally indicated by 228. Alternatively, titaniumaluminum nitride, tantalum aluminum, tantalum aluminum nitride, hafniumsilicon alloy, hafnium nitride, or tantalum carbide may be deposited inopening 218 instead of the titanium aluminum. In opening 220 over thePMOS area 206, optional layers of 10 to 30 angstrom thick titaniumnitride and 10 to 30 angstrom thick tantalum nitride are depositedfollowed by nonoptional layers of 30 to 70 angstrom thick titaniumnitride and 10 to 40 angstrom thick layer of titanium aluminum, whichtogether make up the work function setting metal layer, generallyindicated by 230. Alternatively, tungsten, tantalum nitride, ruthenium,platinum, rhenium, iridium, or palladium may be deposited in opening 220instead of the titanium nitride and titanium aluminum nitride, tantalumaluminum, tantalum aluminum nitride, hafnium silicon alloy, hafniumnitride, or tantalum carbide may be deposited in opening 220 instead ofthe titanium aluminum.

The work function setting metal layers 228, 230 may be deposited asfollows: deposit the optional layer of titanium nitride everywhere,deposit the optional layer of tantalum nitride everywhere, deposit thelayer of titanium nitride layer everywhere, remove the last layer oftitanium nitride from the NMOS area 204 and deposit titanium aluminumeverywhere.

The remainder of openings 218, 220 is filled with a fill metal such asaluminum, titanium-doped aluminum, tungsten or copper (layer 232) toresult in the structure shown in FIG. 2F.

The overburden of the fill metal layer 232, the work function settingmetals 228, 230 and any high-k dielectric layer 226 and cap layers 222,224 are removed by a conventional chemical mechanical polishing processto result in the structure shown in FIG. 2G.

Further middle of the line and back end of the line semiconductorprocessing would then follow.

A process flow for the second exemplary embodiment is illustrated inFIG. 4. The process flow begins by providing a substrate having an NMOSregion and a PMOS region, box 402.

A dummy gate structure is then formed, box 404.

Spacers may then be applied to the dummy gate, if desired, followed bydepositing an oxide interlevel dielectric, box 406.

The dummy gate structure is removed by a suitable etching process toleave open areas where the dummy gate structure used to be, box 408.

The open areas left from the removal of the dummy gate structure arefilled with replacement gates. The replacement gate process begins withthe deposition of lanthanum oxide in the open area over the NMOS regionor deposition of aluminum oxide in the open area over the PMOS region orboth lanthanum oxide in the open area over the NMOS region anddeposition of aluminum oxide in the open area over the PMOS region, box410.

High-k dielectric is then deposited in the open areas and over thelanthanum oxide (if present) and the aluminum oxide (if present), box412.

Then, work function setting metals are deposited to partially fill theopen areas, box 414, followed by deposition of fill metal to fill theremainder of the open areas and complete the replacement gate process,box 416.

The semiconductor structures 100, 200 have been shown as beingplanarized. It is also within the scope of the present exemplaryembodiments to apply the exemplary embodiments to a nonplanar FinFETstructure. The metals must be able to be applied conformally. Instead offilling the openings with titanium aluminum, instead analuminum-containing conformal metal such a titanium aluminum nitride ortantalum aluminum nitride is conformally applied.

It will be apparent to those skilled in the art having regard to thisdisclosure that other modifications of the exemplary embodiments beyondthose embodiments specifically described here may be made withoutdeparting from the spirit of the invention. Accordingly, suchmodifications are considered within the scope of the invention aslimited solely by the appended claims.

What is claimed is:
 1. A semiconductor device comprising: an NMOS regionand a PMOS region; the NMOS region having a gate structure comprising afirst high-k gate dielectric, a first work function setting metal and agate electrode fill material; the PMOS region having a gate structurecomprising a second high-k gate dielectric, a second work functionsetting metal and a gate electrode fill material; wherein the first gatedielectric is different than the second gate dielectric and the firstwork function setting metal is different than the second work functionsetting metal.
 2. The semiconductor device of claim 1 wherein the firsthigh-k gate dielectric constant includes lanthanum.
 3. The semiconductordevice of claim 2 wherein the first high-k gate dielectric and lanthanumare in separate layers with the lanthanum underneath the first high-kgate dielectric.
 4. The semiconductor device of claim 1 wherein thesecond high-k gate dielectric includes aluminum.
 5. The semiconductordevice of claim 4 wherein the second high-k gate dielectric and aluminumare in separate layers with the aluminum underneath the second high-kgate dielectric.
 6. The semiconductor device of claim 1 wherein thefirst high-k gate dielectric includes lanthanum and wherein the secondhigh-k gate dielectric includes aluminum.
 7. The semiconductor device ofclaim 1 wherein the first work function setting metal comprisesaluminum, titanium aluminum, titanium aluminum nitride, tantalumaluminum, tantalum aluminum nitride, hafnium silicon alloy, hafniumnitride, or tantalum carbide, and the second work function setting metalcomprises titanium nitride, tungsten, tantalum nitride, ruthenium,platinum, rhenium, iridium, or palladium.
 8. The semiconductor device ofclaim 1 wherein the first work function setting metal sets the workfunction at the silicon conduction band edge and the second workfunction setting metal sets the work function at the silicon valenceband edge.
 9. The semiconductor device of claim 1 wherein the PMOSregion further including a layer of silicon germanium underneath thesecond high-k gate dielectric.
 10. A method of making a semiconductordevice comprising: providing a substrate having an NMOS region and aPMOS region; forming a high-k dielectric layer over the NMOS region andthe PMOS region; incorporating a metal into the high-k dielectric layerover at least one of the NMOS region and the PMOS region wherein themetal is lanthanum if incorporated into the high-k dielectric over theNMOS region and the metal is aluminum if incorporated into the high-kdielectric over the PMOS region; depositing a nitride or carbide layerover the NMOS and PMOS regions; depositing a silicon layer over thenitride layer; patterning a gate structure of the nitride layer and thesilicon layer over the NMOS and PMOS regions; applying an interleveldielectric between the gate structure over the NMOS region and the gatestructure over the PMOS region; removing the silicon layer from the gatestructure over the NMOS region and the gate structure over the PMOSregion to leave an opening in the gate structures; depositing a firstwork function setting metal in the opening over the NMOS region anddepositing a second work function setting metal in the opening over thePMOS region to partially fill the openings; and depositing a fill metalto fill the openings.
 11. The method of claim 10 wherein the firsthigh-k gate dielectric includes lanthanum.
 12. The method of claim 10wherein the second high-k gate dielectric includes aluminum.
 13. Themethod of claim 10 wherein the first high-k gate dielectric includeslanthanum and wherein the second high-k gate dielectric includesaluminum.
 14. The method of claim 10 wherein the first work functionsetting metal comprises aluminum or titanium aluminum and the secondwork function setting metal comprises titanium nitride.
 15. The methodof claim 10 wherein the first work function setting metal sets the workfunction at the silicon conduction band edge and the second workfunction setting metal sets the work function at the silicon valenceband edge.
 16. The method of claim 10 wherein the PMOS region furtherincludes a layer of silicon germanium underneath the high-k gatedielectric.
 17. A method of making a semiconductor device comprising:providing a substrate having an NMOS region and a PMOS region; forming agate structure on each of the NMOS region and the PMOS region; applyingan interlevel dielectric between the gate structure over the NMOS regionand the gate structure over the PMOS region; removing the gate structureover the NMOS region and the gate structure over the PMOS region toleave an opening in the interlevel dielectric over each of the NMOSregion and the PMOS region; depositing at least one of: lanthanum oxidein the opening over the NMOS region, aluminum oxide in the opening overthe PMOS region; depositing a high-k dielectric in each of the openingsover the NMOS region and the PMOS region; depositing a first workfunction setting metal in the opening over the NMOS region anddepositing a second work function setting metal in the opening over thePMOS region to partially fill the openings; and depositing a fill metalto fill the openings.
 18. The method of claim 17 wherein lanthanum isdeposited in the opening over the NMOS region.
 19. The method of claim17 wherein aluminum is deposited in the opening over the PMOS region.20. The method of claim 17 wherein lanthanum is deposited in the openingover the NMOS region and wherein aluminum is deposited in the openingover the PMOS region.
 21. The method of claim 17 wherein the first workfunction setting metal comprises aluminum, titanium aluminum, titaniumaluminum nitride, tantalum aluminum, tantalum aluminum nitride, hafniumsilicon alloy, hafnium nitride, or tantalum carbide, and the second workfunction setting metal comprises titanium nitride, tungsten, tantalumnitride, ruthenium, platinum, rhenium, iridium, or palladium.
 22. Themethod of claim 17 wherein the first work function setting metal setsthe work function at the silicon conduction band edge and the secondwork function setting metal sets the work function at the siliconvalence band edge.
 23. The method of claim 17 wherein the PMOS regionfurther includes a layer of silicon germanium.